Large-scale purification of pachydictyol A from the brown alga <i>Dictyota dichotoma</i> obtained from algal wash and evaluation of its antifouling activity against the freshwater mollusk <i>Limnoperna fortunei</i>

Abstract

A scalable procedure was developed for the extraction and purification of pachydictyol A, the main diterpenoid isolated from the brown alga <i>Dictyota dichotoma</i>. The organic extract of this species is a complex mixture of a large variety of diterpenes, and in this work, the protocol was employed successfully for the purification of gram quantities of this compound from Patagonian D. dichotoma collected from algal wash. Pachydictyol A, together with other minor diterpenoids, was tested for antifouling activity against the invading freshwater mussel <i>Limnoperna fortunei</i>, using a byssal thread formation assay. The results obtained in the study showed a potent antifouling activity for pachydictyol A at 4.7 μg cm⁻² disk load. As for the other diterpenoids, dictyoxide was also considerably active, while dictyol C and dictyotadiol had a considerably lower activity. Taking into account the large biomass of algal wash and the abundance of <i>D. dichotoma</sup>, together with the effectiveness of the purification protocol, these results show that pachydictyol A and dictyoxide have a good chance to become natural, non-toxic, and ecologically friendly additives in antifouling paints for the protection of submersed structures against <i>L. fortunei</i>.